Hi,
I have this Willem 5.0 Eprom programmer that I have bought from Ebay.
I have bought it for some older eproms that I need to program.
With newer 27C256 and 27C512 it works ok, but with older 27128 and 2716 it does not because of the voltage drop on VPP.
It has a potentiometer (in the red square) that can be used for VPP adjusting but under load I am unable to do that. It does not go higher than ~10V.
I have tried both USB power and external power (from a laptop PSU that can provide max 5A).
The inductor for the step-up part is in the green circle in the picture. It looks like a small capacitor,nothing written on it.
@dl324 -> thanks for the info in the other thread.
I have found this site :
http://www.py2bbs.qsl.br/willem_pcb45en.php
where the author describes an inductor that should replace the original (number of turns, diameter, etc). But when I have replaced mine with that one, max VPP is even lower, so it seems that it is not ok.
This is the picture of the willem. Any advice?
I have this Willem 5.0 Eprom programmer that I have bought from Ebay.
I have bought it for some older eproms that I need to program.
With newer 27C256 and 27C512 it works ok, but with older 27128 and 2716 it does not because of the voltage drop on VPP.
It has a potentiometer (in the red square) that can be used for VPP adjusting but under load I am unable to do that. It does not go higher than ~10V.
I have tried both USB power and external power (from a laptop PSU that can provide max 5A).
The inductor for the step-up part is in the green circle in the picture. It looks like a small capacitor,nothing written on it.
@dl324 -> thanks for the info in the other thread.
I have found this site :
http://www.py2bbs.qsl.br/willem_pcb45en.php
where the author describes an inductor that should replace the original (number of turns, diameter, etc). But when I have replaced mine with that one, max VPP is even lower, so it seems that it is not ok.
This is the picture of the willem. Any advice?